The Nu River: China’s Biodiversity Epicenter

What comes to mind when you think of the words “China” and “environment”?

Most people will conjure images of cities obscured by smog, rivers choked by massive dams, and a denuded countryside. But tucked away in the country’s southwest corner is a magnificent, undammed river that’s a hotspot of biodiversity and a beacon of ecological hope in a country thirsty for it. It’s called the Nu River.

Last month, we convened a research trip that brought scientists to survey a 618 km segment of the Nu River in Yunnan province. Scientists know they need to understand this region better in order to protect it. What they found astonished them.

China’s Disappearing Rivers

It’s no secret that development and growth have put a huge strain on China’s environment. But if the air pollution is bad, the situation for rivers is even more dire. In the past thirty years, more than half of China’s 50,000 rivers have disappeared.

They’ve vanished due to climate change, the over-extraction of groundwater, rapid urbanization, poor management, water and soil loss, contamination and damming.

And yet despite the overwhelming loss of rivers in the country, China remains the source of some of the world’s mightiest rivers. The Tibetan plateau in China hosts the headwaters for some of the most important rivers in all of Asia.

One of these is the Nu River. It flows from the Tibetan plateau and makes its way through Burma and Thailand, where it becomes known as the Salween River, before reaching the Andaman Sea in Southeast Asia. The Nu/ Salween River is 2,815 km in length and its river basin is one of the largest in Southeast Asia.

An Epicenter of Biodiversity

The Nu River crosses a World Heritage Site in China, and it’s an epicenter of biodiversity. The area contains over 6,000 plant species, and scientists believe it supports over 25% of the world’s (and 50% of China’s) animal species.

There are astonishing numbers. In its description of the area, UNESCO explains that it "may be the most biologically diverse temperate region on earth."

Though it has been threatened with dam construction multiple times , the Nu River remains the last of Southeast Asia’s great rivers to be undammed on its main stem.

In fact, protecting the Nu River was one of the most significant victories of the nascent Chinese environmental movement back in 2004. After much lobbying, river protectors won a major victory when Premier Wen Jiabao announced the suspension of all projects along the river, including a cascade of dams that would have generated more power than the Three Gorges Dam.

In 2014, however, the discussion on damming the Nu River was reopened, and 5 dams in Yunnan province are now being reconsidered.

Researchers on the trip observed the distribution of plant and animal species. Their conclusion? They believe reservoirs would pose multiple threats to the area. Biologists noted that the natural forest and vegetation at lower altitudes are not represented in the higher altitudes, which means that if these areas were flooded, plant species would be lost.

Dams would also affect the Nu River’s valley mist. In the upper reaches of the Nu, valley mist is an important component in maintaining delicate ecosystems. Changes in land cover and the development of reservoirs will affect the mist and therefore the ecosystems that need it.

Orchids, for example, are dependent on the valley mist. The scientists observed few wild orchids in the forests, yet tourist areas had numerous species for sale. The scale of selling relative to the quantity observed in the wild presents a significant risk of extinction to a number of the 77 species of orchids – three of which can only be found in the Nu area.

Dams would also further endanger fish. The Nu River basin is critical area for migratory fish species, and observed species have already decreased markedly in diversity and populations. The fact that many have not been captured since 2008 leads scientists to believe that they are extinct.

And there’s still more to discover about the Nu River basin. In fact, one of the researchers on the trip believes that he has discovered new a plant species. He’s been observing the sample that he’s brought back to his laboratory to see how it grows and develops over the coming weeks and months.

Orchid along the Nu River, October 2015

Li Xiao Long

What’s Next for the Nu?

The Nu valleys are some of the most biodiverse in the world, and are valuable as “climate refugia” – places worth preserving in order to allow species to retreat to cooler, more suitable climates as temperatures rise .

It’s difficult to fully appreciate the importance of the complex ecosystems that make up the Nu River basin. The wealth of biodiversity makes the region seem resilient, but every component hangs in delicate, fragile balance. The health of China, its people and economy as well as that of downstream communities is tightly linked to the health of this river.

For more information about the Nu River and the work of our China Program, please contact Stephanie.